Plumbing components when disposed in the external environment, or as commonly termed “outside” must have some form of protection from the freezing of the fluid disposed within the plumbing components in below freezing weather. As the freezing of the fluid disposed within the plumbing components causes the fluid to typically expand volumetrically and by the nature of being confined within the plumbing components, i.e. piping, valves, elbows, and the like. This freezing fluid can exert outwardly expanding forces as against the internal surfaces of the plumbing components that are quite significant, possibly leading to fracture of the plumbing component sidewall, plate, cap, cover, or other plumbing component(s) which of course can lead to disastrous consequences. Wherein this plumbing component fracture while not only failing the component(s) can potentially allow the pressurized fluid within the plumbing components to be released into the external environment in an uncontrolled manner, hence compromising safety via the fluid being in the external environment along with the economic loss associated therewith.
Looking at particular to the automatic or manual permanently installed lawn sprinkler systems arts, wherein there is usually an “outside” exposed number of plumbing components that typically include piping, on/off ball type valves, smaller ball type bleeding valves, and an anti siphon valve assembly. Thus this is the interface between typically the municipal water supply system and the sprinkler feed/distribution system for the lawn, wherein the siphon valve (usually as per government building codes) prevents any water backflow from the sprinkler feed/distribution system back into the municipal water supply system. Should a reverse pressure situation occur, wherein the sprinkler feed/distribution system would have a higher internal pressure than the municipal water supply system, with the purpose being to prevent contamination of the potable municipal water system from the potentially non-potable contaminates disposed within the sprinkler feed/distribution system.
Usually, if an external environment freezing situation occurs with the water disposed within the exposed sprinkler plumbing components freezing, the weakest structural plumbing component link will rupture when internal force is created as against the internal walls on the exposed plumbing components, which is typically the anti siphon valve which will rupture. As the anti siphon valve normally has the largest surface area exposed to force resulting in the anti siphon valve experiencing the highest stress normally leading to the anti siphon valve fracturing, and unfortunately the anti siphon valve is typically the most expensive component of the exposed sprinkler system plumbing components. However, the anti siphon valve typically being the most physically accessible plumbing component for replacement, as opposed to the adjacent piping or aforementioned valves being more difficult to replace due to their location and/or more permanently affixed nature to the sprinkler system.
Normal procedure for sprinkler systems when the freezing colder weather months are approaching is to turn off the ball valve to the municipal water supply and then drain and in combination with a compressed air blowing out, the sprinkler system downstream of the closed ball valve that is in fluid communication with the municipal water system, wherein the municipal water supply valve is located in a non-freezing area, such as within a heated building or underground below the frost line, typically 3 feet or more below the ground surface. However, in the “real” world not all of the residual water is totally removed from within the sprinkler system, in addition, the external environment weather transfer from non-freezing to freezing weather is not usually a specific point in time during the change of seasons, in that a freezing may be light of hard depending upon how long and how far the outside temperate drops below freezing, also wind, humidity, sun exposure, and the like all play a role and this is coupled with the uncertainty of a first light freeze to hard freeze in the change of seasons.
Other factors related to the physical aspects of water freezing further add to the uncertainty of the water hard freezing point in time, being in the “latent heat of fusion” of the internal water freezing in going from liquid to semi-frozen slush, to being hard frozen solid also depend upon the rate of heat transfer from the water to the external environment. Plus the mass or volume of the water present which affects the “thermal diffusivity” of the specific water volume, all work to add to the uncertainty of when the water will freeze solid, wherein the plumbing component damage can occur, versus the water becoming a semi frozen slush, which will most likely not cause plumbing component damage. The result of all this is that frequently the sprinkler system can still be full of water during a sudden unexpected early freeze near the beginning of the cooler season, or the sprinkler system can be turned off prematurely, wherein the lawn is exposed to a warm dry period extending into the cooler weather season without the benefit of the sprinkler system, causing harm to the lawn. The result is that even with the best of precautions, freezing of the exposed plumbing components of the sprinkler system is very possible.
Thus, for the water contained within the plumbing components to move from a liquid state to a solid thus going to a hard freeze state, a specific amount of heat must be transferred out of the water to the surrounding external environment. This heat transfer occurs via three typical processes, being heat radiation, heat convection, and heat conduction, wherein the heat transfer always going from a warmer source to a cooler source, or in other words a heat transfer in going from the water to the surrounding external environment. Heat transfer radiation occurs without any consideration of a medium of which to transfer the heat in, an example would be the sun radiating heat to the earth wherein the heat transfer occurs through the vacuum of space and through the Earth's atmosphere. Thus, the control of heat transfer radiation as effectuated by the ability to either reflect or absorb the radiation, depending upon the desired outcome wherein reflecting the radiation directs the heat back to its source and absorbing the radiation disposes the heat transfer energy to be within the absorbing medium. A radiation reflection medium would be a highly smooth polished and lightly colored reflective surface as contrasted to a radiation absorption medium that would typically have a rough surface and be dark in color.
In looking at heat transfer convection is where the heat energy is carried within a third medium between a heat source and a cooler external environment, a typical example would be in an automotive internal combustion engine cooling system wherein the antifreeze is the third medium that is pumped in between the cylinder walls of the engine and flows to the radiator that has many small passages for which the heat in the third medium can be transferred into the surrounding atmospheric air, thus heat transfer convection is the most efficient means of heat transfer being typically used where a maximum of heat needs to be transferred within a limited amount of space.
Further, in looking at heat transfer conduction in comparing to heat transfer convection the third medium is removed in the heat transfer is solely by the thermal energy of atomic motion directly through materials that are adjacent to one another. In comparing heat transfer conduction to heat transfer convection, heat transfer conduction allows much less heat transfer to occur and that would thus not be a choice for situation where a high heat transfer were desired.
Thus, in the present invention the goal is to absolutely minimize the amount of heat transfer, therefore the three modes of heat transfer named radiation, convection, and conduction need to each be dealt with independently to minimize the amount of overall heat transfer from the water present within the plumbing components to the surrounding external environment, thus resulting in slowing down the water entering into the hard freezing state even though the surrounding external environment is at a below freezing temperature. Noting from the aforementioned analysis above the primary mode of heat transfer to minimize his convection, as he transfer convection is the most efficient in transferring the maximum out of heat this is the heat transfer mode the must absolutely be minimized, wherein radiation and conduction are also minimized, however, having a less significant effect on minimizing overall heat transfer.
This issue is well-recognized in the prior art wherein there are a number of apparatus that attempt to address the above referenced problem. One prior example is in U.S. Pat. No. 4,142,565 to Plunkett Sr. wherein disclosed is an insulating device for fluid conduit for the transport of fluid at a temperature different from the temperature of the immediately surrounding ambient atmosphere that may be quickly and efficiently protected against thermal transport by an insulating device. The device in Plunkett Sr. comprising an elongating sheet of flexible heat insulating material having a length terminated by a top edge and a bottom edge, having a width slightly greater than the equatorial dimension of the fluid conduit and terminated by a first side edge and a second side edge and having an interior conduit-facing side an exterior side, and means for releasably securing the elongated sheet about the fluid conduit.
Plunkett Sr. is basically a hook and loop fastener attached blanket that loosely envelopes the diversely shaped plumbing components constructed of a neoprene sheet, there is no teaching related to special sheet layering, or radiation heat transfer issues, further, the partially non-adjacent nature of the neoprene sheet to the plumbing components would allow for some degree of convection, all of which would lessen the thermal insulating qualities of the Plunkett Sr. device. Further, Plunkett Sr. fails to address the air gap pocket problem leading to increased convection between the pipe and the cover in heat transfer and also does not address the pipe to ground interface problem for loss of heat of the pipe in a cold environment. Plunkett Sr., is merely a folded over neoprene sheet that sandwiches plumbing components providing a minor degree of thermal insulation as between the environment and the plumbing components.
Continuing in the prior art in looking at U.S. Pat. No. 6,820,639 to Petschek, which is basically the same design as Plunkett Sr., in so far as the sheet sandwiching the plumbing components being attached at the sheet outer edges via a hook and loop fastener. Specifically, Petschek discloses a thermal cover for backflow prevention assemblies of a sprinkler system with a thermally lined top wall, opposed thermally lined side walls, fixedly closed end walls, and a variable shaped bottom opening with the side walls flexing outward to allow the cover to spread apart and fit down over the backflow prevention assembly. An adjustable bottom closure in Petschek is closed and fits around at least one pipe extending through the bottom of the cover to close the bottom opening, also a second embodiment further has variable shaped openings along both opposed end walls to allow pipes connected to the backflow prevention assembly to extend through the ends as well as through the bottom. These end openings in Petschek are selectively opened and closed with adjustable end closures, with this embodiment opening up to a flat blanket like configuration.
Velcro-type co-acting first and second fastening members are disclosed in Petschek as an adjustable closure for both the bottom and sides, plus a disclosed thermal cover protects backflow prevention assemblies in case of a short overnight hard freeze, or during extended periods of ambient air temperatures hovering at or below the freezing mark, see Column 1, lines 54-67, and Column 2, lines 1-8. However, Petschek suffers from the same shortcomings as Plunkett Sr., in so far as the air gap and pipe ground interface as previously discussed that adds to the convection heat transfer, Petschek does address radiation heat loss from the pluming components 13, however, placing a radiation layer in the outer surface, see column 3, lines 5-25, which would not be optimal as the radiation would be minimized due to traveling through the insulation for reflection back to the plumbing components 13.
Further Petschek does not address the significant loss of thermal insulating qualities of the sheet at the hook and loop fastener or Velcro interface areas, see in particular FIG. 2, as the insulating walls 17 and 18, completely disappear at the Velcro interface 38 and 41, leaving the pipe with very little thermal insulation, see FIG. 4, at or near the ground to pipe interface, see FIG. 5. Given that the pipe is usually constructed of copper material, which conducts heat very well, the pipe ground interface in Petschek, see FIG. 5, pipe element 15 would very efficiently conduct heat away from the valves, see element 13 in FIG. 5, to the colder ambient environment, thus greatly lessening the anti-freezing properties of the insulation walls 17 and 18 for the plumbing components 13.
Moving next to U.S. Pat. No. 6,520,201 to Sweeney et al. disclosed is an insulated backflow device cover comprising a flexible outer cover, an insulated bag removably attached inside the outer cover such that the outer cover and insulated bag define an interior cavity. Further included in Sweeney et al., is a sealing structure attached to the insulated bag and positioned so as to removably seal the interior cavity of the insulated bag about the fluid transport system, and a plurality of securing structures interconnecting the outer cover and the insulated bag so as to removably secure the device to the region of the fluid transport system. In another aspect of the Sweeney et al., invention, the device includes at least one layer of radiant barrier material and at least one layer of air retaining material.
In one alternative aspect in Sweeney et al., the radiant barrier material and air retaining material are placed in alternating layers. In another alternative aspect of Sweeney et al., the radiant barrier material and air retaining material are placed in alternating layers with the device being made of materials that are unattractive nesting or food materials to animals, birds, insects, plants, or fungi. The materials in Sweeney et al. also absorb less than 20% by weight of water are resistant to exposure to sunlight and temperature extremes; see Column 2, lines 7-32. Sweeney et al. is similar to Petschek in general configuration and thus also has the same previously discussed drawbacks, however, Sweeney et al. does have the layered configuration in materials for more heat transfer efficiency and recognizes the importance of blocking or reducing radiation heat transfer by virtue of the reflective barrier foil.
However, Sweeney et al., as previously mentioned has Petschek's loose fitting and air gap space issues in conjunction with not having an effective pipe/ground interface heat transfer insulation, see FIGS. 1 and 2, which expose the high heat transfer piping (being usually constructed of copper) to the surrounding external environment that will act to accelerate the heat loss from the piping components to the surrounding external environment along with the potentially circulating air gap around the piping components that will further the undesirable increase in heat transfer from the piping components to the surrounding external environment. In summary, Sweeney et al., has a better insulating cover than Petschek for the cover itself, however, still lacks in the air gap and pipe/ground interface areas as described.
Further, in the heat transfer restriction prior art area in U.S. Pat. No. 6,206,030 to Barthuly, disclosed is an insulating cover for water backflow prevention apparatus in the nature of a pillow slip made of thermal insulating material, preferably with a waterproof outside surface and a heat-reflecting inside surface. The cover in Barthuly has an open bottom end like a pillow slip but with a closed hem containing a relatively dense liquid or fluid-like solid granular or pelletized or powered material surrounding the bottom opening. The cover in Barthuly is foldable flat or in any desired configuration for storage. To cover the backflow preventer apparatus in Barthuly, according to the method of the invention, the cover is installed open end down, over the backflow prevention apparatus, and the entire perimeter of the lower edge is engaged with the ground surface.
The fill material in Barthuly, being heavy, holds the cover down on the ground and, being fluid-like, enables the perimeter of the open end to engage the contour of the ground throughout the perimeter to provide an effective cover-to-ground seal. Apertured tabs in Barthuly are provided at the hem to enable installation of anchor stakes, if desired, see column 2, lines 6-26. Barthuly takes into consideration the issue of the pipe interface with the ground heat transfer problem previously described by adding a flanged heavier ground interface that can accommodate an uneven ground surface, see FIG. 1, however, still having the air gap heat transfer problem as previously described, only at an even greater extent as the air gap volume is significantly more than Petschek and Sweeney et al., providing a greater volume of air to undesirably absorb heat away from the piping components, thus potentially freezing the water disposed within the plumbing components sooner.
Continuing in the heat transfer reduction prior art in U.S. Pat. No. 3,941,159 to Toll disclosed an insulation assembly only for a tubular conduit pipe wherein the material is water and vapor proof, corrosion resistant, and flame retardant, it requires no adhesive or banding. The fabric covering in Toll may be supplied in various colors if desired, to permit color identification of different pipeline services, see column 1, lines 53-57. A length of insulation material in Toll is wrapped about an article to be insulated. A layer of fabric is affixed in Toll to the insulation material, one end of the fabric being of a length to overlap the opposite end thereof. Fastening means in Toll are on the overlapped ends of the fabric provide a secure connection of the fabric about the insulation material. Toll shows the key issue of “adjacent” i.e. no undesirable air gap between the pipe and the cover insulating material to the pipe outer diameter; however, Toll does not address the convoluted configuration issue of having a multitude of plumbing components such as valves, siphons, elbows, and the like, as Toll would not be able to accommodate the desirable no air-gap design about non-symmetrical plumbing components, such as a valve. Further, Toll does not recognize radiation heat transfer as a means for reducing overall heat transfer from the piping outer surface.
There remains a need for a more efficient heat transfer reducing apparatus that can better help prevent freezing of the water in the exposed plumbing components and thus the fracturing failure of typically the anti-siphon valve as previously described. A new more efficient heat transfer apparatus would utilize air-gap volume reducing technology along with multiple layering to help the exposed plumbing components to retain what little heat they have to help keep the water disposed within from freezing, thus preventing the undesirable plumbing component damage as previously described. This air gap volume reducing technology would have to reduce the convective heat transfer, which is the most significant heat transfer to reduce, noting that even minimal amounts of air movement (being less than one mile per hour air velocity) around the plumbing components, resulting from slight air temperature differences around the plumbing components can increase the heat transfer from the water in the plumbing components to the surrounding external environment multitudes of times in comparison to the heat transfer from conduction alone.
Thus reducing this air gap as much as possible to prevent or minimize air flow and to reduce the volumetric mass of air around the plumbing components that is heated by the plumbing components is important to minimizing the overall heat transfer from the water to the surrounding external environment. Reducing this air gap around the oddly shaped plumbing components has two distinct challenges, the first one being that the external surfaces of the multiple plumbing components which are typically piping, elbows, ball shutoff valves, bleed valves, and the anti-siphon water backflow prevention valve are all randomly spaced from one another forming a quite uneven surface, which practically necessitates a custom fitted insulating enclosure around the previously described plumbing components to accommodate the practically infinite variety of plumbing component arrangements spacing and sizing.
The second distinct challenge in reducing this air gap from the custom fitted insulating enclosure, is a the enclosure must be easily removable for the required physical access to all of the previously described valves. Further desirable features on the custom fitted insulating enclosure would for it to be water proof, as water entrainment into the insulation would have a detrimental effect on increasing heat transfer through the insulating enclosure and for it to seal tightly when the custom fitted insulating enclosure is re-attached to the plumbing components. Thus, these two previously mentioned challenges embody the novel requirement of the present invention, as noted in the discussion of the prior art the devices typically are a mere blanket or large pocket of some sort that loosely drapes over the plumbing components, wherein this has the effect of allowing large air gaps in the multitude of places around the plumbing components which facilitates heat transfer convection which leads to higher rate of heat transfer from the water disposed within the plumbing components to the surrounding external environment and the resulting undesirable situation of the water freezing sooner. This would be accomplished with the more efficient heat transfer reducing apparatus without the need of any additional heating elements and the like, resulting in the heat transfer apparatus being “Green” i.e. more energy efficient, not requiring any ongoing energy to operate, thus being totally self contained not requiring for example an electrical heating element to prevent freezing that would need an outside electrical power source.